According to the California Air Resources Board (CARB), 70% of diesel particulate matter (PM) is emitted from off-road mobile sources, of which 54% is traceable to off-road construction equipment. Diesel particulate is categorized as a Toxic Air Contaminant (TAC) by CARB. A strategy that has proven very cost-effective for reducing harmful TACs is the re-powering of existing off-road construction equipment with new, cleaner heavy-duty diesel engines. The existing non-regulated engine is removed from the vehicle and scrapped. A new, CARB certified engine is then installed. In addition to reductions in particulate matter TACs, this strategy also results in significant reductions in oxides of nitrogen (NOx), an ozone precursor.
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Sukut identified twelve (12) Caterpillar 651B scrapers equipped with approximately 20 year old Caterpillar Model D346 diesel engines. Due to the size of the equipment, it was decided to perform the equipment re-powers in the field as opposed to a mechanic's shop. Sukut identified a select staff of qualified heavy-equipment mechanics and supervisors to perform the engine installations. By using in-house staff and performing the re-power installation in the field, the equipment downtime was minimized. New Tier 3 Caterpillar C15 engines were used for the re-power. These new engines are certified at a NOx level of 2.32 g/bhp-hr and PM level of 0.088 g/bhp-hr and are approximately 500% cleaner than the engines replaced. While heavy-duty diesel engines are routinely removed and replaced for overhaul purposes in this type of equipment, the latest generation of electronically controlled diesel engines incorporate computer systems, sensors, and wiring harnesses not incorporated on the existing older vehicles. Thus, an engine re-power entails considerably more work than simply removing and replacing the engine; wiriing harnesses, larger radiators, sensors, etc., must be retrofitted into the older vehicle. The electronic sensors required for reporting real-time engine data to the on-board computer system had to be installed where none previously existed. This required that Sukut invest in laptop computers and specialized training for the field mechanics so they could start, analyze, and tune the new engines to achieve optimum efficiency and emissions using Caterpillar's engine management software.
The objective of this project was to re-power twelve (12) exisiting heavy-duty diesel scrapers with new Tier 3 diesel engines, thereby reducting both PM and NOx emissions. Sukut Construction, Inc., is the owner and operator of these off-road construction vehicles and acted as the prime contractor on this Clean Transportation Funding project.
The results of this re-power project were extremely successful. The new engines are certified at Tier 3 and are literally five times lower emitting than the engines replaced. Performing the re-power operations in the field significantly reduced the downtime associated with the engine replacements.
The re-powering of all twelve Caterpillar 651B scrapers was completed as of June 19, 2006. All equipment re-powers were successful and the vehicles are currently operating on construction projects within the South Coast Air Quality Management District jurisdiction.